Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['m', '3669', '2989', '1101', '4181', 'u', 'h', '9973', '7929', '1541', '897']

h, m, u